Easiest way to make sure files are erased?

Discussion in 'Macintosh Computers' started by hikeNM, Dec 13, 2005.

  1. hikeNM macrumors 6502a

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    #1
    I've always heard that even if you trash a file and empty the trash, someone who knows what they are doing(which is not me) can still retrieve that file on your hard drive, even though you "erased" it.

    First off, is this true?

    If it is, how do I make sure I completely erase files from my hard drive?

    Thanks
     
  2. iGary Guest

    iGary

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  3. grapes911 Moderator emeritus

    grapes911

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    #3
    Yes it's true, but it takes a lot of work. Finder --> Secure empty trash does a better job, but with the right technology the deleted files could still be reconstructed.
     
  4. yellow Moderator emeritus

    yellow

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    #4
    1) Yes, sort of. It's not easy. 9 times out of 10 they would require physical access to the drive. It's not like they can just stumble upon erased files.. plus the more you use your disk, the higher the likelihood that the block on the disk will be overwritten, smashing all the data (making the file unrecoverable).

    2) What iGary said. Secure delete overwrites the blocks with 0s. 7x, I believe.
     
  5. hikeNM thread starter macrumors 6502a

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    #5
    Will reinstalling the OS secure erase everything?
     
  6. plinkoman macrumors 65816

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    #6
    no. neither will reformatting.

    when something is deleted, the physical bits on the hard drive are not actually changed, they are still there, but they are no longer accessible(by normal means) and the next time you write to the disk, it will begin to overwrite those bits.

    what is so important that you delete without a trace?? i can't imagine anything so important that a secure empty trash wont be enough.

    if your really paranoid, just write a ton of stuff to the disk after deleting whatever it is.
     
  7. hikeNM thread starter macrumors 6502a

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    #7
    LOL----No, I just saw a Law & Order episode where somebody had "erased" something and the detectives took the hard drive to their techs and they retrieved the data.

    Just a not-tech wondering about this box I sit in front of for 10 hours a day.
     
  8. semaja2 macrumors 6502a

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    #8
    well when u delete something normally it just deletes the file from a table of reference which refers to every files and its location, a secure erase will actially reset all the 1/0 on the hdd of that files location, a normal reformat will just wipe the table but a full reformat will wipe the whole hdd making every piece of data reset to 0
     
  9. Eidorian macrumors Penryn

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  10. hikeNM thread starter macrumors 6502a

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    #10
    Is a full reformat an option when youre reinstallling the OS?
     
  11. plinkoman macrumors 65816

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    #11
    well, unless you're planning on committing a crime and having related documents to it backed up on your hard drive, i wouldn't worry about it ;)
     
  12. semaja2 macrumors 6502a

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    #12
    a full format is a option in windows im not sure about macosx since iver never done it before, but im guessing its in their somwhere. but i also belive theres a option in there to do a secure format?
     
  13. virus1 macrumors 65816

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  14. yellow Moderator emeritus

    yellow

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    #14
    When booting from the installer CD/DVD, you can run Disk Utility and under the Erase tab, there's plenty of options for levels of secure erasing.

    In Panther's (and pre-panther) version of Disk Utility there's a "zero all data" which is a single pass erase, writing zeros in place of all 1s/0s. It's possible that there's another level, but I don't have any Panther boxes left to check it on.

    In Tiger's version of Disk Utility, there's MANY more layered options. It all depends on your level of paranoia. There's single pass, 7-pass, and 35-pass. Note that each level requires that much longer to reformat your drive.
     
  15. Moof1904 macrumors 65816

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    #15
    I few years ago I read in some DARPA publication that super secret spy folks were working on some kind of tunneling electron beam that would be able to retrieve data that had been securely overwritten multiple times, ala Secure Empty Trash. Haven't heard anything else on the project, though.

    I contracted on a classified project involving fighter aircraft a while back and the U.S. Gov't required that at the conclusion of the project, the hard drives from every computer used on the project be removed and physically crushed to teenie little bits under their supervision. None of the existing "secure erase" technologies were approved for use on this data. The drives had to be crushed.

    For 99.99999999% of us, Apple's Secure Empty Trash is more than sufficient. For the rest, only crushing the drive to smithereens will do. :eek:
     
  16. yellow Moderator emeritus

    yellow

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    #16
    I think passing the drive through a very high magnetic field will do too..
     
  17. macmanmatty macrumors regular

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    #17

    Nope, there is only one way to completely erase everything off of your harddrive Thermite!!!!


    The FBI has taken all kinds of info of formatted, magnetically wiped, cut up, smashed, zeroed, and other kinds. Thermite is only way to make sure your data is never recovered by anyone.
     

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